In general, a paved road must be finished to a level surface.
One current method for finishing the paved surface of the road and making it level requires using curbstones or the gutter on the edge of the road as the reference plane (or line) according to which the paved surface can be finished.
Another method for finishing the paved surface of the road requires a use of an averaging beam (about as long as the tractor unit) which is placed along the side of a tractor unit in the travelling direction and by considering the unpaved surface of the road as a approximately flat.
To operate such conventional leveling machines, the operator must have knowledge of the pavement conditions including the type of mixed asphalt material to be used, the pavement width, and the pavement thickness. Moreover, the operator must run the machine while watching the actual surface to be paved.
Regarding the former method of using curbstones for the reference plane, curbstones are not always found on the edge of the road to be paved. Moreover, when curbstones are available for the reference plane, the flatness of the ground may be gradually degraded as the distance from the curbstones increases.
The latter method requires an averaging beam, involving the use of large equipment. With larger paving equipment, operations are difficult on narrower roads. The averaging beam can be used only after the base preparation has been completed to some degree to diminish unevenness. In spite, the averaging beam method cannot control the thickness of the pavement.
The conventional leveling machine depends on the operator's sense for operation. The operator's skill often affects the quality of leveling; it is, therefore, difficult to always achieve an excellent finish with the conventional leveling machine.
This new automatic leveling machine is designed to be automatically operated In accordance with the operating conditions such as the type of mixed asphalt material, pavement width, and pavement thickness. This information is entered into the control unit from the keyboard.
However, it is troublesome to enter such operating conditions into the control unit from the keyboard at the site. In addition, typing in data from the keyboard takes time and mistakes are very easy to make.